A switched mode power supply (power converter, SMPS) as provided in FIG. 1 is an electronic power supply that incorporates switching regulator 110 to convert electrical power efficiently. Like other power supplies, an SMPS transfers power from source 120, for example, mains power, to load 130, such as a personal computer, while converting voltage and current characteristics. Unlike a linear power supply, pass transistor 140 of a switched mode power supply continually switches between low-dissipation, full-on and full-off states, and spends very little time in the high dissipation transitions, which minimizes wasted energy. Ideally, a switched mode power supply dissipates no power. Voltage regulation is achieved by varying the ratio of on-to-off time. In contrast, a linear power supply regulates the output voltage by continually dissipating power in the pass transistor. This higher power conversion efficiency is an important advantage of a switched mode power supply.
Switching regulators may be used as replacements for linear regulators when higher efficiency, smaller size or lighter weight are required. They are, however, more complicated; switching currents can cause electrical noise problems if not carefully suppressed, and simple designs may have a poor power factor.
In an SMPS, the output current flow depends on the input power signal, the storage elements and circuit topologies used, and also on the pattern used (e.g., pulse-width modulation with an adjustable duty cycle) to drive the switching elements. The spectral density of these switching waveforms has energy concentrated at relatively high frequencies. As such, switching transients and ripple introduced onto the output waveforms may be filtered.
Although a switching power supply may offer greater efficiency, disadvantages include greater complexity, the generation of high-amplitude, high-frequency energy that the low-pass filter must block to avoid electromagnetic interference (EMI), a ripple voltage at the switching frequency and the harmonic frequencies thereof.
A power converter's transient performance is subject to uncertainties and non-idealities in the components and controller. These non-idealities can deteriorate response to dynamic changes in the system and/or cause the system to approach instability. Prior art solutions to this problem have included automatic one-time or continuous adjustment of the control parameters based on frequency response techniques. There are heretofore unaddressed needs with these previous solutions.